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  • Writer's pictureJen Haynes

Mogulones Crucifer Controls Houndstongue

Houndstongue (Cynoglossum officinale) is a biennial invasive plant that is native to Europe. It grows to just over a metre tall. It has reddish purple flowers and oblong leaves that are hairy and rough like a dog’s tongue. Most people know this plant by its burred, Velcro-like seeds. Anyone who has had burrs stuck to their shoes and socks has most likely been in contact with a houndstongue plant. Apart from the burrs being annoying to pick from your clothes and pets, houndstongue has other impacts. It is poisonous to livestock. They will avoid eating it in the pasture, so the poisoning usually occurs when they eat it dried in hay. It has also been known to cause dermatitis in humans. The good news is that in Canada we have a biocontrol agent called mogulones crucifer. These weevils do a fantastic job of controlling houndstongue! The weevils are round, 2-3mm long, brown with a white cross on their back. They can fly so they can spread to infestations of houndstongue easily. The adults feed on the leaves leaving round holes in the leaves. They also feed on the stems, flowers, seeds, and the larva feed on the roots. They are the silver bullet of biocontrol. Most biocontrol agents only feed on one or two parts of the plant. As with all biocontrol, there are up and down cycles. Houndstongue is the food that mogulones crucifer needs to survive so they will never fully eradicate the plants as it is their food source. We are currently in a bit of an upswing in houndstongue in the Boundary but if you check the leaves, you will see the tell-tale signs of the weevils being present. You will not often see the weevils, but they are there. If you have houndstongue on your property and you would like to eradicate it, you can cut the tops off where the seed is and bag it. This will stop it from going to seed while still allowing the larva in the root to finish developing. It is free to take bags of invasive plant to the landfill. For more information on invasive plants and biological control contact the Boundary Invasive Species Society at, 250-446-2232, and on Facebook.

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